Process for preparing lubricant compositions and concentrates therefor



Aug. 18, 1959 w. LOWE PROCESS FOR PREPARING LUBRICANT COMPOSITIONS ANDCONCENTRATES THEREFOR Filed March 13, 1958 R V. \V o E /l T N qwm NN Rmm WM 0 T 53.5w R T 5 68 E UI\ M A 5300mm I ww Y km \mw m t o ozEGEEj Evw miow 2 9u uj zti 10.55. E f uz 2 2? t 3 3 States PROCESS FURPREPARING LUBRICANT CUMPU- SITIUNS AND CONCENTRATES THEREFOR ApplicationMarch 13, 1958, Serial No. 721,127 Claims. arm-33.4

The present invention relates to a superior new process for preparinglubricant compositions and concentrates therefor. More particularly, theinvention is concerned with a novel method of producing additive typelubricating oil compositions and concentrates for preparing them whichcontain greatly increased amounts of the effective additive in stablecombination.

Lubricating oil compositions are subject to deterioration by oxidationwhich results in the formation of corrosive products, particularly inmodern internal combustion engines where stringent operating conditionsare encountered. These corrosive products attack the bearings and othermetal surfaces in the engine, and additives are ordinarily employed toinhibit their corrosivity. In order for the additives to perfonneffectively during the service of the lubricating oil composition, it isimportant that adequate amounts of the additive be present at all timesin stable combination with the lubricating oil base. Still largerproportions of additives are required, of course, in the concentrateswith which the corrosion inhibited lubricating oil compositions areprepared.

Unusually effective corrosion inhibited lubricating oil compositionscomprising lubricating oil and a phthalic acid have been described inapplication Serial No. 478,517, Lowe and Stewart and application SerialNo. 478,838, Stewart and Lowe, both filed December 29, 1954, and nowboth abandoned. Although the compositions described in theseapplications have very greatly improved corrosion inhibiting propertiescompared to previously known lubricant compositions containingconventional corrosion inhibitor additives, the phthalic acids are soslightly soluble in lubricating oils that there is a limit to the amountthat can be stably dispersed by simply adding them to the base oil. Thedesirability of a process whereby larger amounts of the phthalic acidscan be combined in stable form with an oil of lubricating viscosity is,therefore, even greater in the case of these very important types ofcorrosion inhibited lubricating oil compositions and concentrates fromwhich they are prepared.

It has now been found that stable dispersions of phthalic acids in oilsof lubricating viscosity can be prepared by a process which comprisesreacting a phthalic acid with a tertiary amine, combining the reactionmixture thus obtained with an oil of lubricating viscosity, heating thecombined oil and reaction mixture to liberate the tertiary amine andseparating the tertiary amine and the resulting dispersion of phthalicacid in oil of lubricating. viscosity.

In the superior new process of this invention as described above, thereis provided a remarkably straightforward means for the production oflubricating oil compositions and concentrates for preparing them whichcontain substantially larger amounts of phthalic acid than haveheretofore been possible. Particularly in the case of lubricating oilconcentrates, the outstanding advantages of the present process are mostappreciated, since it is of the utmost importance for practical reasonsthat 2,900,339 Patented Aug. 18, .1959

a pressure and the separations are made by the use of conventionalprocedures.

Still another outstanding advantage of the process of the invention liesin the fact that the tertiary amine may be recovered and recycled forfurther use. Although the tertiary amine is not an unusually expensivereagent, this provides more effective use of it, contributing to overallefiiciency, and gives a definite economic advantage to the process.

In the practice of the invention, the phthalic acid is first reactedwith the tertiary amine, as already mentioned. The acid is thusconverted to its tertiary amine salt. Although the tertiary amine may beemployed in any amount sufficient to neutralize the acid, astoichiometric excess is preferred. This insures complete reaction, andany excess tertiary amine is readily recovered in accordance with theprocess of the invention. Usually proportions of at least 20 to 40 molesof tertiary amine per mole of phthalic acid will provide a very suitablereaction mixture for dispersion in the lubricating oil. In a preferredembodiment the amount of tertiary amine employed is suflicient todissolve all of the phthalic acid tertiary amine salt. amine has beenfound to act as a cosolvent for both the phthalic acid tertiary aminesalt and the oil of lubricating viscosity with which it is combined.More thorough dispersion of the tertiary amine salt in the oil is thuspossible.

The reaction of the phthalic acid with the tertiary amine in the presentprocess is conveniently carried out at ordinary temperatures and underordinary pressures. Room temperatures of about 77 F. are particularlysuitable, since they require no heating or cooling of the reactants.Higher temperatures can be employed to accelerate the reaction andfacilitate the dissolving of the tertiary amine salt. However,temperatures in excess of 600 F. are preferably avoided, since thephthalic acids tend to sublime when overheated. For similar reasons itis also desirable'that the reaction temperature not exceed the boilingpoint of the tertiary amine at the particular pressure employed duringthe reaction. Usually temperatures of from about F. to 500 F. aresuitable. Where solvents such as benzene and toluene are employed, it isparticularly convenient to allow the reaction mixture to reflux, thusmaintaining temperatures at the boiling points of, the respectivesolvents.

The pressure at which the reaction is carried out may be eitheratmospheric, subatmospheric or superatmosphen'c. However, atmosphericpressures are preferred, since the need for pressure equipment or vacuumequipment is thus avoided.

The phthalic acid of the process may be either phthalic acid,isophthalic acid or terephthalic acid. These acids are commerciallyavailable and require .no detailed description here. For presentpurposes, the nonanhydrideforming benzene dicarboxylic acids such asisophthalic acid and terephthalic acid and their nuclear substitutedanalogues such as hexahydrometaphthalic acid, hexahydroparaphthalic acidand S-tertbutylisophthalic acid are preferred. The most suitable acidsare the isophthalic acid and terephthalic acid, more particularly thelatter, since they give lubricant compositions which are-unusuallyeffective corrosion inhibitors.

The tertiary amine with which the phthalic acid is reacted may be anybasic tertiary amine capable of forming thermally unstable. salts ofthe, phthalic acid. Such In such a case the excess tertiary tertiaryamines maybe any of the well-known, commonly available types having thegeneral formula in which R R and R may be the same or diflerentaliphatic, aryl, aryl aliphthatic or hydroxy aliphatic groups. Eithertwo or all three of the valence bonds to these groups may be combined toform a single group as in the case of cycloaliphatic or heterocyclictertiary amines. Preferably, the tertiary amines boil below about 600F., the temperature which the phthalic acids tend to sublime. Moreparticularly the preferred tertiary amines are those having the aboveformula in which R R and R contain a total of from 5 to 15 carbon atoms.Illustrative tertiary amines include triethylamine,N,N-dimethyl-N-benzylamine, N,N-dimethylaniline, N-methylpiperidine,pyridine, picoline, triethanolamine and the like. For present purposes,pyridine, picoline and triethylamine are preferred in the ordermentioned for their particularly suitable physical characteristics andgeneral availability. These tertiary amines illustrate the more suitableclass of tertiary hydrocarbon amines containing a total of from 5 to 15carbon atoms although the alkyl, hydroxyalkyl and heterocyclic aromatictertiary amines of the abovementioned illustrative types are generallysatisfactory.

As mentioned above, solvents may be employed in the reaction of thephthalic acid with the tertiary amine. This facilitates the handling ofthe reactants and can be I used to provide automatic temperaturecontrols, if desired,

for the reaction. a

Any of the well-known types of oils of lubricating viscosity aresuitably employed in the preparation of the lubricant compositions andlubricating oil concentrates in accordance with the process of theinvention. They include hydrocarbon or mineral lubricating oils ornaphthenic, paraftinic, and mixed naphthenic and paraffinic types. Theymay be refined by any of the conventional methods such as solventrefining and acid refining. Synthetic hydrocarbon oils of the alkylenepolymer type or those derived from coal and shale may also be employed.Alkylene oxide polymers and their derivatives such as the propyleneoxide polymers and their ethyl esters and acetyl derivatives in whichthe terminal hydroxyl groups have been modified are also suitableSynthetic oils of the dicarboxylic acid ester type including dibutyladipate, di-Z-ethylhexyl sebacate, di-nhexyl fumaric polymer, di-laurylazelate and the like may be used. Alkyl benzene types of synthetic oilssuch as tetradecyl benzene, etc., are also included. Liquid esters ofacids of phosphorus including tricresyl phosphate, diethyl esters ofdecane phosphonic acid, and the like may also be employed. Also suitableare the polysiloxane oils of the type of polyalkyl-, polyaryl-,polyalkoxyand polyaryloxy siloxanes such as polymethyl siloxane,polymcthylphenyl siloxane and polymethoxyphenoxy siloxane and silicateester oils such as tetraalkyland tetraaryl silicates of thetetra-Z-ethylhexyl silicate and tetra-p-tert.-butylphenyl silicatetypes. The process of the invention is particularly adapted to thepreparationof stable dispersions in mineral lubricating oils and suchoils are preferred accordingly. i The lubricating oil of the lubricantcompositions prepared in accordance with the process of this inventionmay be employed in amounts of from about 100 to 100,000 times, on aweight basis, the amount of phthalic acid in the reaction mixture. Thismeans that the final lubricant composition will contain from about 0.001to about 1.0% by weight of phthalic acid based on the total composition.The ratio of phthalic acid in the reaction mixture to the lubricatingoil is preferably such that the final lubricant composition containsfrom about 0.001 to about 0.5% by Weight of the phthalic acid. Thepresent process is particularly suitable for producing stabledispersions of more than 0.15% by weight of phthalic acid in minerallubricating oil whereas the usual direct methods of adding phthalic acidto lubricating oil do not give more than about 0.15% of acid in stabledispersion. In the production of lubricating oil concentrates forblending with oils of lubricating viscosity in the preparation ofcorrosion inhibited lubricant compositions, the phthalic acid reactionmixture may be combined with amounts of lubricating oil such that theconcentrate contains up to 10% by weight or more of the phthalic acid.The most suitable concentrates, however, from the standpoint ofstability and resistance to precipitation of the additive under storageconditions and the like are those containing from about 3 to 8% byweight of phthalic acid based on the total composition and theproportions of lubricating oil to phthalic acid are regulatedaccordingly.

The reaction mixture of phthalic acid and tertiary amine may be combinedwith the oil of lubricating viscosity by various means. Agitation of thetwo components is desirable to insure uniform distribution. This may bedone by blowing with an inert gas such as nitrogen 'or stirring withmechanical stirrers. The operation may be carried out at ordinarytemperatures, but slightly higher temperatures of from about to about F.may be advantageously employed to facilitate mixing of the "phthalicacid and tertiary amine reaction mixture with the lubricating oil.

The combined oil and reaction mixture are heated to liberate thetertiary amine. The temperature at which the tertiary amine salts ofphthalic acid will decompose and permit the tertiary amine to be drivenoff is approxi mately the boiling point of the .tertiary amine.Preferably, this temperature should not exceed 600 F., the temperatureat which the phthalic acids tend to sublime.

The tertiary amines produced by the decomposition of the tertiary aminesalts and the excess tertiary amine in the reaction mixture areconveniently separated from the dispersion of phthalic acid inlubricating oil by simple distillation at temperatures equal to theboiling point of the tertiary amine. The tertiary amine thus separatedmay be recovered by condensation for further use.

Any excess phthalic acid which will not remain in stable dispersion inthe oil of lubricating viscosity is separated from the stable dispersionof phthalic acid in oil by conventional methods for separating solidsand liquids such as decantation, filtration and the like.

' The lubricating oil compositions and concentrates for preparing themderived by the process of this invention may also contain conventionallubricating oil additives which are known to the art. In a preferredembodiment of the invention the lubricating oils and concentratestherefor will contain lubricating oil detergents to aid the oil incarrying off insoluble decomposition products which are normally formedduring ordinary service. 'These detergents are selected from the betterknown classes such as the metal salts of naphthenic acids, for example,aluminum naphthenate; metal salts of fatty acids and substituted fattyacids, for example, calcium stearate, calcium phenyl stearate, basiccalcium phenyl stearate and calcium dichlorostearate; metal salts ofaromatic acids and substituted aromatic acids, for example, calciumoctyl salicylate; metal salts of petroleum sulfonic acids, for example,calcium sulfonate and basic calcium sulfonate; metal salts of alkylphenol sulfides, for example, barium amyl phenol sulfide; metal salts ofalkyl phenols, for example, aluminum dicetyl phenate and calcium dicetylphenate; metal salts of thiophosphoric acid esters, for example, thezinc salt of the p-tert.amylphenyl ester of dithiophosphoric acid; andmetal salts of wax substituted phenol derivatives, for example, the waxsubstituted metal phenatcs. Nonmetallic lubricating oil detergentadditives which are also suitable include macromolecular copolymerscharacterized by oil solubilizing .monomer groups and polar type monomergroups such as the copolymers of methacrylic acid and laurylmethacrylate. Dispersants, as illustrated by the phosphatides such asanimal lecithin and the partial or complete esters of long chaincarboxylic acids with polyhydric alcohols such as pentaerythritolmono-oleate and glycerol sorbitan laurate may also be present. Stillother additives such as pour depressants, viscosity index 'iriiprover's,wear inhibitors and the like which are commonly employed in lubricantcompositions can be included when desired.

The above additives may be present in amounts up to 20% by weight of thefinal lubricant composition. In the preparation of concentrates, amountsup to 50% by weight or more may be employed. For present purposes,however, very superior lubricant compositions are provided by thepresent process when the additive is eniployed in amounts of from 0.1 toby Weight of the composition.

In a preferred embodiment of the process according to the presentinvention .stable'dispersions of more than 0.15% by weight ofterephthalic acid are prepared in a mineral lubricating oil containingcalcium petroleum sulfonate which oil analyzes at least 0.20 percent byweight calcium. The process is particularly adaptable to the preparationof stable dispersions in the form of lubricating oil concentrates ofmore than 0.25 percent by weight of terephthalic acid in a minerallubricating oil analyzing at least about 4.0 percent by weight calciumattributable to calcium petroleum sulfonate.

The following examples are oifered in further illustration of theinvention and show simplified procedures for producing lubricating oilcompositions and concentrates therefor containing substantially greateramounts of phthalic acid than possible by means employed heretofore.Unless otherwise specified, the proportions are on a weight basis.

Example I In this example, the preparation of a stable dispersion ofterephthalic acid in mineral oil containing a conventional lubricatingoil detergent and an oil stabilizing agent is illustrated, both for theproduction of lubricating oil concentrates and lubricating oilcompositions for internal combustion engines.

400 gm. of a lubricating oil detergent concentrate of calcium petroleumsulfonate and a solvent refined mineral lubricating oil base analyzing1.71% by weight calcium and 308 gm. of a concentrate of a sulfurizedcalcium alkyl phenate sludge inhibitor or stabilizer in a solventrefined mineral lubricating oil base analyzing 4.43% by weight calciumare charged to a reaction vessel equipped with stirrer, thermometer,addition funnel, distillation column and heating means. 500 ml. ofbenzene is then added. The mixture is stirred at 150 F. for about 20minutes.

In a separate vessel, 42.7 gm. of terephthalic acid is dissolved in 1000ml. of pyridine with stirring at room temperature. The resultingreaction mixture of pyridine terephthalate dissolved in pyridine is thencombined in the reaction vessel with the mineral lubricating oilconcentrate of detergent and stabilizing agent mentioned above. Benzeneand pyridine are continuously distilled off under a reduced pressureequal to about 20 mm. mercury, while the terephthalic acid and reactionmixture is-being added. Benzene is occasionally added to dilute themixture until a total volume of 500 ml. is used.

The combined mineral lubricating oil concentrate and terephthalic acidpyridine reaction mixture are heated to about 250 F. This decomposes thepyridine terephthalate to liberate the pyridine. The pyridine andresidual benzene are separated by stripping the contents of the reactionvessel to 350 F. at 2 mm. mercury pressure.

The mineral lubricating oil concentrate obtained by the procedureoutlined above analyzes 2.75% by weight calcium in the form of calciumpetroleum sulfonate and ,20 1nm./kg. sulfurized calcium cetyl phenateand 0.25%

by weight terephthalic acid. In a standard L4 engine test this lubricantcomposition gave a bearing weight loss of only 57 mg. and an enginecleanliness of 9.8 compared to a bearing weight loss of more than 500mg. and

a cleanliness of 3.5 obtained with a similar lubricant compositioncontaining no terephthalic acid.

Example 11 In this example, there is employed the same general method asthe preceding example illustrating the process of the present invention.The base oil is another variety of compounded mineral lubricating oilfor internal combustion engines.

The reaction flask is charged with 277 gm. of a calcium petroleumsulfonate concentrate in a solvent refined mineral lubricating oil basewhich analyzes 4.19% by weight calcium. 17.5 gm. of terephthalic acid in1000 m1. of pyridine is then added. The mixture is heated and stirred asabove. The pyridine is distilled off by heating to 350 F. at 2 mm.mercury pressure.

The concentrate contains 6.2% by weight terephthalic acid in completelystable form as evidenced by its bright, clear appearance. It remainsstable on standing for several days at room temperature withoutnoticeable formation of haze or precipitates.

4.075% by weight of the concentrate in a 60 VI solvent refined SAE 40mineral lubricating oil base gives a superior lubricant compositioncontaining 40 mm./kg. calcium petroleum sulfonate and 0.25% by Weightterephthalic acid. Such a composition is. capable of outstandingperformance in internal combustion engines,

both from a standpoint of detergency and corrosion inhibition, as shownby its performance in tests described in the previously mentioned patentapplications on phthalic acid corrosion inhibited lubricating oils.

Additional examples of preparations of stable dispersions ofterephthalic acid in mineral lubricating oil in accordance with theprocess of this invention were carried out using the procedure of theforegoing examples. The mineral lubricating oil was a solvent-refinedSAE 30 oil and the sulfonate, as indicated by the percent by weightcalcium, was a calcium petroleum sulfonate. The data from these examplesare given in the following table.

The outstanding advantages of the novel process of this invention inproducing superior lubricant compositions and concentrates therefor isplainly evident from the above examples. By previous methods of addingterephthalic acid to lubricating oil compositions, it is not possibleordinarily to incorporate more than about 0.15 to 0.25% by weight ofterephthalic acid if stable dispersions are to be obtained. By way ofcontrast, the process of the present invention permits the incorporationof terephthalic acid in amounts of more than 0.15% ranging up to 5.7% byweight or more, as shown by the above examples, to give remarkablystable dispersions.

As an additional example providing a more graphic illustration of theprocess of the present invention, attention is invited to theaccompanying drawing which shows a simplified flow diagram of stillanother embodiment of the invention.

Referring to the drawing, a tertiary amine of the type described aboveis introduced via line 11 to reaction vessel 12. The phthalic acid ofthe aforementioned type is added to the reaction vessel through conveyor13. .A stoichiometric excess of tertiary amine is preferably employed.The reactionvessel is equipped with mechanical TABLE Sulfonate,Terephthalic Mole Ratio of Appearance of Fin- Percent bv Acid, Tertiaryished Oil Containing Example N o. Tertiary Amine Wt. Cal- Percent byAmine to Terephthalic Acid i cium in Wt. in Oil Tcrephthalic AfterStanding Acid One Week Pyridine 0. 42 1. 0 100:1 No Precipitate.

do 0. 21 0. 25 400:1 D0. Triethylamine 0. 84 0. 2 300:1 Do. do 0.42 0.2300:]. Do. do 0. 21 0.2 300:1 D0. Pimline O. 84 O. 2 420:1 Do. do 0. 210.2 420:1 D0. Triethanolamine 0. 84 0. 2 345:1 Do. rlo 0.21 0.2 345:].D0.

N 0.42 0.1 White Precipitate.

do 0. 42 0.05 D0.

stirrer 14 and heating coils 16 as means for facilitating reaction ofthe tertiary amine and phthalic acid and solution of the resultingtertiary amine salt of phthalic acid in the excess tertiary amine. Anyvolatilizcd tertiary amine occurring during the preparation of thetertiary amine and phthalic acid reaction mixture is vented through line17.

The reaction mixture of tertiary amine and phthalic acid is withdrawnvia line 18 to disperser 19 which is provided with stirrer 21 andheating coils 22. Lubricating oil, which may contain other conventionallubricating oil additives, is added to the disperser via line 23. Ifdesired for convenient handling, a solvent may be introduced throughline 24. The lubricating oil and tertiary aminephthalic acid reactionmixture are combined with stirring and heating to give a dispersion ofthe tertiary aminephthalic acid reaction mixture in lubricating oil.Volatilized solvent and tertiary amine occurring at this stage of theoperation are vented through line 26.

The combined oil and tertiary amine-phthalic acid reaction mixture areremoved from disperser 19 and carried through line 27 to heater 28. Herethe oil and reaction mixture are heated to decompose the tertiary aminesalt of the phthalic acid and liberate the tertiary amine. During thedecomposition, the mixture of oil, phthalic acid and tertiary amine areagitated by stirring means 29.

From heater 28, the tertiary amine and dispersion of phthalic acid inoil are conveyed via line 31 to separator 32 equipped with heating means33. The tertiary amine and the dispersion of phthalic acid in oil areseparated by distilling off the tertiary amine via line 34.

The dispersion of phthalic acid in oil is withdrawn from separator 32via line 36 throughcooler 37 and line 38 to settler 39. In settler 39any phthalic acid not held in stable dispersion is settled out andwithdrawn via line 41. The final product, which is a stable compositionof phthalic acid and oil of lubricating viscosity, is withdrawn fromsettler 39 via line 42.

In a cyclic process, the undispersed phthalic acid from settler 39 isreturned via conveyor 41 to conveyor 13 and where it is introduced againto the process described above. Tertiary amine vapors from reactor 12and disperser 19 are conveyed via lines 17 and 26, respectively, to line34,

where they are combined with the solvent and tertiary amine fromseparator 32. The tertiary amine and solvent are conveyed via line 34 tofractionator 43 where they are separated by conventional means, as forexample, by fractional distillation. From fractionator 43 the tertiaryamine fraction is returned via line 44 to line 11 where 'it isintroduced again to the process, as outlined above.

The solvent fraction is returned to the process in the same fashion vialines 46 and 24. 4

In the above descriptions of the superior new process in accordance withthis invention it will be noted that the invention also includes aremarkably effective new corrosion inhibited lubricant composition whichcontains the effective corrosion inhibitor, phthalic acid, in unusuallylarge amounts of above 1.0% by weight or more and preferably by weightor more based on the total composition. These unusually large amounts ofphthalic acid corrosion inhibitor, particularly isophthalic acid andterephthalic acid, provide unusually outstanding lubricant compositions,since the eifective ingredient is present in amounts suflicient toinhibit corrosion throughout prolonged periods of service. The novellubricating oil additive concentrates prepared by the method of theinvention which contain 10% by weight or more of the phthalic acidpossess similar unusual advantages over previously known compositions.It would appear that none of these superior new compositions werecapable of existing prior to the present process.

This application is a continuation-in-part of Warren Lowe patentapplication, Serial No. 506,449, filed May 6, 1955, and now abandoned.

I claim:

1. A process for producing stable dispersions of more than 0.15% byweight of terephthalic acid in a mineral lubricating oil which comprisesreacting terephthalic acid with a tertiary amine selected from the groupconsisting of tertiary hydrocarbon amines and tertiary hydroxy alkylamines containing a total of from 5 to 15 carbon atoms in proportions ofat least 20 moles of tertiary amine per mole of terephthalic acid,combining the reaction mixture thus obtained with the minerallubricating oil containing calcium petroleum sulfonate, which oilanalyzes at least about 0.2% by weight calcium, heating the combined oiland reaction mixture to liberate the tertiary amine and separating thetertiary amine and the resulting dispersion of terephthalic acid inmineral lubricating oil.

2. A process for producing stable dispersions of more than 0.15% byweight of terephthalic acid in a mineral lubricating oil which comprisesreacting terephthalic acid with a tertiary hydrocarbon amine containinga total of from 5 to 15 carbon atoms in proportions of at least 20'moles of tertiary amine per mole of terephthalic acid, combining thereaction mixture thus obtained with the mineral lubricating oilcontaining calcium petroleum sulfonate, which oil analyzes at leastabout 0.2% by weight calcium, heating the combined oil and reactionmixture to liberate the tertiary amine and separating the tertiary amineand the resulting dispersion of terephthalic acid in mineral lubricatingoil.

3 A process for producing stable dispersions of more than 0.15% byWeight of terephthalic acid in a mineral lubricating oil which comprisesreacting terephthalic acid with pyridine in proportions of at least 20moles of pyridine per mole of terephthalic acid, combining the reactionmixture thus obtained with the mineral lubricating oil containingcalcium petroleum sulfonate, which oil analyzes at least about 0.2% byweight calcium, heating the combined oil and reaction mixture toliberate the pyridine and separating the pyridine and the resultingdispersion of terephthalic acid in mineral lubricating oil.

4. A process for producing stable dispersions of more than 0.25% ofterephthalic acids in a mineral lubricatin; oil which comprises reactingterephthalic acid with pyridine in proportions of at least 2() mols ofpyridine per mol of terephthalic acid, combining the reaction mix turethus obtained with a mineral lubricating oil containing calciumpetroleum sulfonate, which oil analyzes at least 4.19 percent by weightcalcium, heating the combined oil and reaction mixture to liberate thepyridine and separating the pyridine and the resulting dispersion ofterephthalic acid in mineral lubricating oil.

5. A process for producing stable dispersions of more than 0.25% ofterephthalic acids in a mineral lubricating oil which comprises reactingterephthalic acid with pyridine in proportions of at least 20 mols ofpyridine per mol of terephthalic acid, combining the reaction mixturethus obtained with a hydrocarbon solvent and a mineral lubricating oilcontaining calcium petroleum sulfonate, which oil analyzes at least 4.19percent by weight calcium, heating the combined solvent, oil andreaction mixture to liberate the pyridine and separating the pyridineand the resulting dispersion of terephthalic acid in mineral lubricatingoil.

6. A process for producing stable dispersions of more than 0.25% ofterephthalic acids in a mineral lubricating oil which comprises reactingterephthalic acid with pyridine in proportions of at least 20 mols ofpyridine per mol of terephthalic acid combining the reaction mixturethus obtained with benzene and a mineral lubricating oil containingcalcium petroleum sulfonate, which oil analyzes 4.19 percent by weightcalcium, heating the combined benzene, oil and reaction mixturetoliberate the pyridine and separating the pyridine and the resultingdispersion of terephthalic acid in mineral lubricating oil.

7. A process for producing stable dispersions of more than 0.25% ofterephthalic acids in a mineral lubricating oil which comprises reactingterephthalic acid with pyridine in proportions of at least 20 mols ofpyridine per mol of terephthalic acid combining the reaction mixturethus obtained with benzene and a mineral lubricating oil containingcalcium petroleum sulfonate, which oil analyzes 4.19 percent by weightcalcium, heating the combined benzene, oil and reaction mixture toliberate the pyridine, separating the pyridine and the resultingdispersion of terephthalic acid in mineral lubricating oil and combiningsaid dispersion with mineral lubricating oil to give a lubricantcomposition containing 40 mm./kg. calcium sulfonate and 0.25 percent byweight terephthalic acid.

8. A process for producing stable dispersions of more than 0.15 byweight of terephthalic acid in a mineral lubricating oil which comprisesreacting terephthalic acid with triethylamine in proportions of at least20 moles of triethylamine per mole of terephthalic acid, combining thereaction mixture thus obtained with the mineral lubricating oilcontaining calcium petroleum sulfonate, which oil analyzes at leastabout 0.2% by weight calcium, heating the combined oil and reactionmixture to liberate the triethylamine and separating the triethylamineand the resulting dispersion of telephthalic acid in mineral lubricatingoil.

9. A process for producing stable dispersions of more than 0.15% byweight of terephthalic acid in a mineral lubricating oil which comprisesreacting terephthalic acid with picoline in proportions of at least 20moles of picoline per mole of terephthalic acid, combining the reactionmixture thus obtained with the mineral lubricating oil containingcalcium petroleum sulfonate, which oil analyzes at least about 0.2% byweight calcium, heata ing the combined oil and reaction mixture toliberate the picoline and separating the picoline and the resultingdispersion of terephthalic acid in mineral lubricating oil.

10. A process for producing stable dispersions of more than 0.15% byweight of terephthalic acid in a mineral lubricating oil which comprisesreacting terephthalic acid with triethanolamine in proportions of atleast 20 moles of triethanolamine per mole of terephthalic acid,combining the reaction mixture thus obtained with the minerallubricating oil containing calcium petroleum sulfonate, which oilanalyzes at least about 0.2% by weight calcium, heating the combined oiland reaction mixture to liberate the triethanolamine and separating thetriethanolamine and the resulting dispersion of terephthalic acid inmineral lubricating oil.

References Cited in the file of this patent UNITED STATES PATENTS2,134,736 Reuter Nov. 1, 1938 2,158,096 Werutz May 16, 1939 2,280,474Byrkit Apr. 21, 1942 2,329,474 Lazar et al. Sept. 14, 1943

1. A PROCESS FOR PRODUCING STABLE DISPERSIONS OF MORE THAN 0.15% BYWEIGHT OF TEREPHTALIC ACID IN A MINERAL LUBRICATING OIL WHICH COMPRISESREACTING TEREPHTALIC ACID WITH A TERTIARY AMINE SELECTED FROM THE GROUPCONSISTING OF TERTIARY HYDROCARBON AMINES AND TERTIARY HYDROXY ALKYLAMINES CONTAINING A TOTAL OF FROM 5 TO 15 CARBON ATOMS IN PROPORTIONS OFAT LEAST 20 MOLES OF TERTIARY AMINE PER MOLE OF TEREPHTALIC ACID,COMBINING THE REACTION MIXTURE THUS OBTAINED WITH THE MINERALLUBRICATING OIL CONTAINING CALCIUM PETROLEUM SULFONATE, WHICH OILANALYZES AT LEAST ABOUT 0.2% BY WEIGHT CALCIUM, HEATING THE COMBINED OILAND REACTION MIXTURE TO LIBERATE THE TERTIARY AMINE AND SEPARATING THETERTIARY AMINE AND THE RESULTING DISPERSION OF TEREPHTALIC ACID INMINERAL LUBRICATING OIL.